Multiple functions with same name from same population become one

[arvoelke]

For example,

net.connect('A', 'B', func=lambda x:2*x)
net.connect('A', 'C', func=lambda x:3*x)

This creates only a single origin with name 'lambda', which computes the first function. So the connections to population C are unexpectedly wrong.

This could be fixed in _parse_pre of nef_core.py by appending id(func) to the function name. We could also do something smarter like maintain a dict of name -> id(func), and then only make the names more verbose if a collision is detected (so here the two names would be 'lambda' and 'lambda 1').